The Instituted Acolyte
The acolyte is appointed in order to aid the deacon and to minister to the priest. It is his duty therefore to attend to the service of the altar and to assist the deacon and the priest in liturgical celebrations, especially in the celebration of Mass; he is also to distribute communion as a special minister when the ministers spoken of in the Codex Iuris Canonici can. 845 are not available or are prevented by ill health, age, or another pastoral ministry from performing this function, or when the number of communicants is so great that the celebration of Mass would be unduly prolonged. In the same extraordinary circumstances an acolyte may be entrusted with publicly exposing the Blessed Sacrament for adoration by the faithful and afterward replacing it, but not with blessing the people. He may also, to the extent needed, take care of instructing other faithful who on a temporary basis are appointed to assist the priest or deacon in liturgical celebrations by carrying the missal, cross, candles, etc., or by performing other such duties.
As one set aside in a special way for the service of the altar, the acolyte should learn all matters concerning public divine worship and strive to grasp their inner spiritual meaning: in that way he will be able each day to offer himself entirely to God, be an example to all by his gravity and reverence in church, and have a sincere love for the Mystical Body of Christ, the people of God, especially for the weak and the sick.
In accordance with the ancient tradition of the Church, institution to the ministries of reader and acolyte is reserved to men.
The following are requirements for admission to the ministries:

A. the presentation of a petition that has been freely made out and signed by the aspirant to the Ordinary (the bishop and, in clerical institutes, the major superior) who has the right to accept the petition;

B. a suitable age and special qualities to be determined by the conference of bishops;

C. a firm will to give faithful service to God and the Christian people.
The ministries are conferred by the Ordinary (the bishop and, in clerical institutes, the major superior) through the liturgical rite De institutione lectoris and De institutione acolythi as revised by the Apostolic See.
The Code of Canon Law states:
1035 §1. Before anyone is promoted to the permanent or transitional diaconate, he is required to have received the ministries of lector and acolyte and to have exercised them for a suitable period of time.
§2. There is to be an interval of at least six months between the conferral of the ministry of acolyte and the diaconate.
1036 In order to be promoted to the order of diaconate or of presbyterate, the candidate is to present to his bishop or competent major superior a declaration written in his own hand and signed in which he attests that he will receive the sacred order of his own accord and freely and will devote himself perpetually to the ecclesiastical ministry and at the same time asks to be admitted to the order to be received.